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Research Consensus on Polyphenols

Jan 28, 2005

The Following are a Selection from the Studies and Analysis Presented at the Recent Conference Relating to Fruit and Vegetable Polyphenols - The Studies are Published in the January 2005 issue of The American Journal of Clinical Nutrition

Dietary Polyphenols and Health: Proceedings of the 1st International Conference on Polyphenols and Health

The Effects of Polyphenols on Humans: A Review of 93 Intervention Studies

For some classes of polyphenols there are now sufficient intervention studies to indicate the type and extent of effects on humans in vivo (on humans, not in a test tube):

  • The isoflavones genistein and daidzein found in soy have significant beneficial effects on bone heath among postmenopausal women
  • Green Tea Catechins increase our antioxidant levels and improve energy metabolism
  • Grape Seed OPCs and Resveratrol and other polyphenols from red wine and red grape skins, and the polyphenols in cocoa, cranberry, apple skin, and some similar supplements have strong beneficial effects on the vascular system
  • Quercitin found in onions, apple skins, red wine, broccoli, and green tea helps decrease the risk of cancer by decreasing some cancer markers.
The publishers of the research are from the National Institute of Agronomics Resarch, Saint-Genes Champanelle, France, and the Nestle Reserch Center, Lausanne, Switzerland.

Beneficial Effects of Fruit Polyphenols on Aging and Brain Health

Numerous studies have indicated that individuals who consume large amounts of fruits and vegetables reduce their risk of suffering age related diseases such as Alzheimer's disease. Research from our laboratory (see below*) suggests that dietary supplements with fruit or vegetable extracts high in antioxidants such as blueberry or spinach extracts may decrease the worsening vulnerability to free radicals that occurs with aging.

These improvements may show up as improved mobility and improved cognitive function. Our research shows that it is not just antioxidant and antiinflammatory activities by these nutrients but also improved cell signaling (communication between cells that insures the development of normal-healthy cells) and improved neuronal communication. *The publishing researchers are from the US Department of Agriculture Human Nutrition Research Center on Aging at Tufts University, and The Institute of Pathology, Case Western Reserve University.

Polyphenols and the Inhibition of Cancer

Many plant polyphenols have been shown to have cancer preventing activities in the lab. For example (Green) Tea preparations inhibit tumor formation in a variety of animal models involving cancers of the skin, lungs, mouth and tongue, esophagus, stomach, liver, pancreas, small intestine, colon and prostate. In some cancers the tea is protective throughout the cancer formation cycle of initiation, promotion, and progression (into the cancerous tumor).

Curcumin (Turmeric), Genistein, and Quercetin also have anti-cancer activity. They inhibit cancer cell growth, the transformation into cancer, and also cause the destruction and death of cancer cells. They inhibit metastasis, and inhibit the ability of a cancerous tumor to feed itself. The amounts used in studies are higher than the amounts normally found in foods. The study was authored by researchers from the Ernest Mario School of Pharmac, Rutgers University.

Polyphenols and Cardiovascular Protection

Epidemiological studies suggest that higher intake of polyphenols from fruit and vegetables is associated with a decreased risk of cardiovascular disease. Polyphenols improve the surface function of blood vessel walls and help regulate platelets decreasing the risk of an abnormal blood clot. Imrpoving the function of blood vessel wall cells decreases the risk of coronary artery disease. The positive effect on platelets decreases the abnormal coagulation (blood clotting) seen in acute coronary syndromes including a heart attack and unstable angina. The publishers of the research are from Boston University School of Medicine.